This invention relates to an electronic control fuel injection system for a spark ignition internal combustion engine of the type wherein fuel flow rate is operator initiated and air flow rate is controlled as a function of fuel flow rate and, more particularly to such a system that provides a preselected engine response characteristic for the initiated fuel flow rate.
In copending application Ser. No. 228,973, filed Jan. 27, 1981 now abandoned and assigned to the assignee of this application, an electronic control fuel injection system for a spark ignition internal combustion engine is disclosed wherein air flow rate is controlled as a function of fuel flow rate. The fuel flow rate is transmitted by the operator's depression stroke of an accelerator pedal to a fuel selecting mechanism which determines the fuel flow rate and supplies a signal representative of the selected fuel rate to a computer together with various correction information. Using the selected fuel flow input, the computer calculates an optimum air flow rate and controls a throttle valve in the engine air manifold to provide the optimum air flow. For various engines, or engine/vehicle combinations, the normal or actual engine response characteristic relative to accelerator pedal movement is not desirable or satisfactory. For example, some vehicle operators may wish to have a quicker or more powerful engine response such as might be provided in a relatively light or more powerful vehicle, while others may wish to have a slower response that would provide a higher degree of fuel economy.
Heretofore, in prior engine control systems, some attempts were made to vary the power response characteristics relative to accelerator pedal movement by use of relatively complicated mechanical linkages and/or other mechanisms between the accelerator pedal and the fuel flow control such as the fuel injectors or carburetor. However, such mechanical interconnections were not satisfactory for a range of driving conditions and also were often excessively complex and thus, unreliable and expensive.